In order to register your IRC nickname with the Nickserv, login to an IRC channel. Here I use a web based client for making this process simple and easy.

1. Go to http://webchat.freenode.net.

2. Enter the nickname you wanted to register and any irc channel say #python and click connect.

3. If it isn't already owned you will see a page with logs and at the bottom you can type messages. This is the status page tab. After a while you will see the #python page.

4. Click the status tab and enter /msg Nickserv REGISTER password email where password is the password you want and an email to confirm the nickname. Confirmation message will be sent to your email.

5. Open your mail and follow the instruction.

6. The verification format will be of the form /msg NickServ VERIFY REGISTER yournickname verificationcode

If you don't want to make your email public then enter /msg nickserv set hidemail on.

To set nick to private mode set /msg nickserv set private on so that list command does not show the nick.

Once identified with the server, to change password use /msg nickserv set password $newpass.

Note that you need to login at least once in 60 days to prevent the username from being inactive.

Ref: IRC Beginner's commands